It's a finicky process. Took me about 2 hours per rim to true the wheels on my /5 for the first time.
I would attach a dial indicator to your setup. It'll make truing the side-to-side and up-and-down runout of the rim much easier.
Also, you need to measure the rim offset when truing /5 wheels. This will ensure both wheels are inline, when mounted on the bike, and adequately center between the front forks and rear swingarm. To determine the offset, just place a long straightedge on the drum side and use a caliper to measure the distance between the straightedge and rim. Whomever trues your wheels will need the below reference information.
Hope this helps and keep up the great work!